Patch Pump Plunger Sequencing for Continuous Vial Drug Delivery
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Solution Overview
Problem
Existing wearable drug delivery devices face challenges in efficiently drawing therapeutic substances from standard drug vials without changing the internal dimensions of the reservoir and maintaining continuous delivery while adapting to changes in orientation and volume.
Innovation Solution
A wearable medical patch pump that includes an electromechanical pumping assembly with a plunger mechanism to draw therapeutic substances from a non-collapsible vial into a pump chamber, utilizing an orientation sensor to determine the optimal orientation and volume for drawing, and control circuitry to manage the pumping process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pump draws therapeutic substance from a standard drug vial without changing the internal dimensions of the reservoir, then the device can integrate commercially available vials easily, but vacuum buildup occurs inside the reservoir that prevents continuous drawing
Solution Approach 1:
A gas-permeable, liquid-impermeable membrane is introduced as an intermediary component between the reservoir interior and exterior. This membrane allows gas to enter the reservoir to replace the volume of withdrawn liquid while preventing liquid leakage, thereby eliminating vacuum buildup and enabling continuous pumping without modifying the standard vial structure.
Solution Approach 2:
The membrane's selective permeability parameters are utilized to differentiate between gas and liquid phases. The membrane permits gas molecules to pass through while blocking liquid molecules, changing the pressure dynamics inside the reservoir to maintain continuous flow without vacuum formation.
2Productivity
If the pump operates continuously to deliver therapeutic substance, then the delivery efficiency is improved, but the device orientation relative to gravity affects the ability to draw liquid from the reservoir
Solution Approach 1:
The gas-permeable membrane acts as a mediator that equalizes pressure between the reservoir interior and exterior regardless of device orientation. By allowing gas to freely enter and replace withdrawn liquid volume, the system maintains drawing capability in any gravitational orientation, enabling continuous productivity without orientation constraints.
Solution Approach 2:
The membrane creates an equipotential pressure environment inside the reservoir by allowing gas to equalize pressure differences caused by gravitational effects in various orientations. This eliminates orientation-dependent pressure gradients that would otherwise prevent continuous drawing.
3Strength
If the reservoir is designed as a non-collapsible vial to maintain structural integrity, then the reservoir strength is improved, but the internal volume cannot change to facilitate drawing without vacuum buildup
Solution Approach 1:
The gas-permeable membrane serves as an intermediary that compensates for the fixed volume of the rigid non-collapsible reservoir. By allowing gas to enter and replace withdrawn liquid, the membrane maintains pressure equilibrium without requiring the reservoir to collapse or change shape, thus preserving both structural integrity and continuous withdrawal capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and continuous delivery of therapeutic substances from standard drug vials without vacuum buildup, allowing for easy integration of commercially available vials and minimizing the need for intermediary filling apparatuses.
Implementation Method 1
an orientation sensor coupled to the therapeutic substance delivery device and configured to generate an output indicative of an orientation of the therapeutic substance delivery device with respect to gravity
Implementation Method 2
a pump configured to draw the therapeutic substance from the reservoir into a pump chamber disposed within the therapeutic substance delivery device without changing the internal dimensions of the reservoir, the volume of the therapeutic substance within the pump chamber varying in response to changes in the internal dimensions of the pump chamber
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2B
AI summary
A therapeutic substance delivery device includes a fluid path having a reservoir needle, a body needle, a body needle injection mechanism, and a pumping assembly (a) configured to pump the substance from the reservoir to the subject, (b) shaped to define a pump chamber, and (c) including a plunger disposed within the pump chamber. The plunger moves back and forth through a plurality of discrete motion phases. A first motion phase of the plunger actuates a first operation from a group of operations including (a) driving the reservoir needle to penetrate the reservoir, (b) advancing the body needle into the body of the subject, (c) withdrawing the substance from the reservoir, (d) pumping the substance into the subject, and (e) retracting the body needle. A second motion phase of the plunger actuates a second operation from the group of operations. Other applications are also described.